PBM3960

February 1999 PBM 3960/1 Microstepping Controller/ Dual Digital-to-Analog Converter Description PBM 3960/1 is a dual 7-bit+sign, Digital-to-Analog Converter (DAC) especially developed to be used together with the PBL 3771/1, Precision Stepper Motor driver in micro-stepping applications. The circuit has a set of input registers connected to an 8-bit data port for easy interfacing directly to a microprocessor. Two registers are used to store the data for each seven-bit DAC, the eighth bit being a sign bit (sign/ magnitude coding). A second set of registers are used for automatic fast/slow current decay control in conjunction with the PBL 3771/1, a feature that greatly improves high-speed micro-stepping performance. The PBM 3960/1 is fabricated in a highspeed CMOS process. Key Features Analog control voltages from 3 V down to 0.0 V. High-speed microprocessor interface. Automatic fast/slow current decay control. Full-scale error ±1 LSB. Interfaces directly with TTL levels and CMOS devices. Fast conversion speed, 3 µs. Matches PBL 3771. WR C DA- Data 1 D E1 CS C D R Level 2 R Level 1 Digit Comp E1 C E D R CD 1 DA 1 E E2 A0 E3 C D A1 E4 D7 - D0 C D R R DA- Data 2 D/A E D/A Digit Comp E4 C D R DA E 2 CD 2 E Sign 2 POR RESET R V ss Figure 1. Block Diagram. P B 22-pin plastic DIP 28-pin plastic PLCC M M B /1 P 60 39 E Sign 1 39 PBM 3960/1 60 /1 V DD V Ref PBM 3960/1 Maximum Ratings Parameter Pin no. * Symbol Min Max Unit Voltage Supply Lo...